1. Field of the Invention
The present invention relates to a transmission apparatus capable of transmitting captured image data captured by an imaging unit, and a display control apparatus capable of receiving and displaying the captured image data from the transmission apparatus.
2. Description of the Related Art
Conventionally, there has been known a remote control technique for controlling an imaging direction of a network camera provided with a pan mechanism and a tilt mechanism. For example, Japanese Patent Application Laid-Open No. 2001-69496 discusses that a user remote-controls from a controller 12 the imaging direction of a monitoring camera capable of being endlessly rotated by 360 degrees in a pan direction and being rotated by 180 degrees in a tilt direction.
Further, Japanese Patent Application Laid-Open No. 2007-114503 discusses that a camera platform control apparatus remote-controls the driving of a pan mechanism and a tilt mechanism of a camera platform with an imaging apparatus mounted thereon, or the driving an optical axis rotation of the imaging apparatus.
However, a certain instruction for moving the imaging direction may mislead a user to think that the imaging direction is not appropriately controlled in response to the user's movement instruction.
A more specific example of this case will be described below with reference to FIG. 12. A camera illustrated in FIG. 12 includes a pan mechanism 1601, a tilt mechanism 1602, and a rotation mechanism 1603 capable of being driven by a movement instruction transmitted from a remote site. As illustrated in FIG. 12, the pan mechanism 1601 and the tilt mechanism 1602 each can move only within a limited range.
Further, in the example illustrated in FIG. 12, the pan mechanism causes a rotation of the imaging unit when the pan mechanism changes the imaging direction of the imaging unit, while the tilt mechanism does not cause a rotation of the imaging unit when the tilt mechanism changes the imaging direction of the imaging unit. In this case, the camera may combine driving the pan mechanism, the tilt mechanism, and the rotation mechanism, depending on a movement direction instructed by a user.
For example, it is assumed that a user is viewing a reproduced image based on captured image data transmitted from the camera illustrated in FIG. 12, and then this user inputs a movement instruction to the camera for changing the imaging direction by 10 degrees to the right. The right direction as viewed in FIG. 12 is a different direction from the direction to which the imaging direction can be moved by driving the tilt mechanism 1602. Therefore, for moving the imaging direction to the right, the camera has to control not only the tilt mechanism, which does not cause a rotation of the imaging unit, but also the pan mechanism, which causes a rotation of the imaging unit.
More specifically, referring to FIG. 13, the camera drives the tilt mechanism to move the imaging direction by 10 degrees downward as indicated by the instruction “1” in FIG. 13, and then drives the pan mechanism by 90 degrees as indicated by the instruction “2”. These two control operations result in a movement of the imaging direction of the camera by 10 degrees to the right. However, as indicated by “HOW OBJECT LOOKS ACTUALLY”, the control of the pan mechanism results in a rotation of the displayed image, and therefore the camera further controls the rotation mechanism.
When the camera respectively controls the pan mechanism, the tilt mechanism, and the rotation mechanism in this way according to the movement instruction for moving the imaging direction to the right, the user may misunderstand the situation and tends to think that the camera is not performing an appropriate control in response to the user's imaging direction movement instruction.